1. Field
Embodiments of the present invention relate to technologies for electrical utility load balancing and power management.
2. Description of the Related Art
Smart-grid technology concepts have been in development since the introduction of power electronics some 30 years ago. In particular, many power electronics systems have been used to load balance the electrical grid using both heuristics and user intervention at a very high “macro-management” power level. Utilities are starting to realize the full potential of smart grid applications to manage power on the grid using the Internet and wireless communication techniques. As economies and electrical power consumption grow, it is imperative that grids operate to the highest efficiency levels possible in order to conserve energy resources and reduce carbon emissions into the atmosphere. It has been claimed that a 1% increase in efficiency of the U.S. electrical grid can reduce carbon dioxide (CO2) emissions by 50 billion pounds.
In general, power flow management and power factor correction has been previously done using two methods. One method has been at a high system level, using flexible alternating current (AC) transmission systems (FACTS), and another method has been at the electrical device level, using power factor correction techniques.
FACTS have been proposed in recent years to manage the power flow of transmission grid systems. These devices include phase shifting transformers, impedance modulators, series compensation capacitors and other power electronics based devices which are installed at transmission line stations to adjust power flow in each transmission line. Due to the high voltage associated with transmission lines in the range of 100 to 800kV, the cost of such devices is very high. FACTS require the addition of new components for providing power flow control without exploiting the properties of existing network components. There are two forms of FACTS compensation that are applied to the transmission system, namely shunt and series compensation.
In shunt compensation, the grid or power system is connected in shunt with the FACTS and works as a controllable current source. Shunt capacitive compensation is used to improve power factor on the grid by compensating for inductive loading. Shunt compensation works by injecting reactive current into the line to maintain voltage magnitude. Transmittable active power is increased, but more reactive power has to be provided.
In series compensation, the FACTS system is connected in series with the line and works to modify the line impedance. The impedance is reduced so as to increase the transmittable active power, however, at the same time, more reactive power must be provided.
At the subsystem level or individual device level, power factor correction is performed similarly to a FACTS system but with lower costs and more intelligent control. Capacitive and inductive loading are used in a series or shunt with the load, and power factor correction is performed with additional power electronics that can adjust power factor accordingly. Some newer forms of power factor correction are performed at the device level by intelligently switching the power supplies of the device. Again, there is additional hardware cost associated with these types of devices and no control of load demand operation.
When demand for power increases during peak hours, in some small cases utilities will reduce the voltage production in order to reduce the current consumption of the loads on the grid. This is effective, but only for a few percentage points of reduction, as a last resort, before brown-outs are implemented.
In the U.S., the power flow management in recent years has become very challenging due to a significant integration of power systems across regions of the country. Changes in demand for power at different points in the grid can cause grid congestion, the consequences of which may include price spikes, load dropping and if these measures do not suffice loss of power to one or more areas.
From the foregoing background discussion, it should be apparent to those of ordinary skill in the art that the efficient distribution of power over an electrical grid remains a significant problem especially if one is to factor in the introduction of additional large loads, such as new factories and communities without the building of new power generation plants, for which a solution would be highly desirable. Therefore, in view of the shortcomings of the prior-art technologies, a new method and system for distributing power and controlling to the power flow to non-critical loads over an electrical grid remains highly desirable.